/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/DynamicMeshOctree3.h
Call TriangleFunc for any triangles in the spill set (ie not contained in any Root cell)
void CollectSpillTriangles ( [TFunctionRef](API\Runtime\Core\GenericPlatform\TFunctionRef)< void(int)> TriangleFunc ) const